• Proceedings of the KSR Conference
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• 2005.05a
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• pp.680-685
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• 2005

An active application of concrete track is being expected for the future constructions of Korean railroad. For the successful concrete track construction in earthwork areas, proper reinforced subgrades, which effectively distribute train loads to subground, should be installed. In this paper, behaviors of concrete track on the reinforced subgrade with the standard stiffness and depth were investigated through numerical analyses. The appropriateness of the reinforced subgade was evaluated by analyzing the distributions of the settlements and vertical stress beneath the concrete slab.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.4
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• pp.343-350
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• 2017

The RC flat plate system has benefits such as a short construction time, an improvement of workability and a floor height reduction. In the case of long span slab, cracking damages and large deflections tend to occur due to the low flexural stiffness of flat plates. Specially, over-loading by self-weight of slab during construction increases short and long-term deflections. These problems may be solved by the use of void slab that has benefits of the reduced self-weight. In this study, to analyze an effect of self-weight reduction of void slab on slab deflections, the parametric study is performed. Including variable conditions such as a concrete strength, a slab construction cycle, the number of shored floors, a compressive reinforcement ratio and a tensile reinforcement ratio, slab construction loads and deflections are calculated by considering the construction stages, concrete cracking, and long-term effects. The short-term deflections during construction and the long-term deflections after construction of both of normal and void slabs are compared and the effects of void slab on the reduction of slab deflections are analyzed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.845-856
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• 2020

This study proposes a bridge evaluation system for indivisible permit vehicles such as hydraulic cranes. The permit loads for the bridge evaluation are divided into three categories: routine permit loads, special permit 1 loads, and special permit 2 loads. Routine permit and special permit 1 vehicles are allowed to cross a bridge with normal traffic. For these two permits, the standard lane model in the Korean Highway Bridge Design Code was adopted to consider normal traffic in the same lane. Special permit 2 vehicles are assumed to cross a bridge without other traffic. Structural analyses of two prestressed-beam bridges and two steel box girder bridges were conducted for the proposed permit loads. The rating factors of the four bridges for all permit loads were calculated as sufficiently large values for the moment and shear force so that crossing the bridges can be permitted. A reliability assessment of the bridges was performed to identify the reliability levels for the permit vehicles. It was confirmed that the reliability level of the minimum required strength obtained by the load-resistance factors yields the target reliability index of the design code for the permit vehicles.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.4
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• pp.358-364
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• 2024

Type A carrier structures that support blocks or equipment gradually deform over time with load changes, reducing the area in contact with the block and changing the load pattern from distributed to concentrated during construction work in the shipyard. This phenomenon has the potential to misrepresent actual service loads. In particular, A carriers are often used by small manufacturers, who often do not have specialized engineering capabilities, necessitating the development of a method for easy calculation of carrier safe working load. This study proposes a quick evaluation method for the long-term safe working load of Type A carriers, to predict the plastic deformation and safety issues resulting from changes in load distribution. Based on the results of finite element analysis (beam and shell modeling) of the centralized load, beam-theory was modified to propose a method for determining the distributed load conditions of the A-carrier. In beam modeling, the theoretical value was multiplied by a correction factor of 0.73 for concentrated loads and 0.69 for distributed loads to obtain a safe working load. For shell modeling, a correction factor of 0.75 can be used for concentrated loads and 0.69 for distributed loads. This study can serve as a basis for improving the safety of shipbuilding, enabling quick and effective decisions for determining safe working loads in actual working environments.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.1
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• pp.39-47
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• 2016

Repair methods of aging concrete pavement are generally used composite structure pavements, such a composite structure is subjected to a large impact on the mechanical behavior and ensure long-term commonality integrated under vehicle loads, environmental loads of the public in accordance with the bond strength between old and new concrete. A common of bonded concrete overlays that are currently available is Interface arrangements using a variety of equipment to ensure the excellent bond strength between old and new concrete than standard concrete, mixed with a material such as a polymer in order to improve the adhesion with the material itself. However, these method of constructions are being applied, depending on the developer site presents no special specifications apply when a specific application criteria objectively, this is due to the situation of each individual method, which is based on the difficulty in quality control of the site manager. In this study by performing a field test for polymer content via the variables that contribute most significantly to ensure bond strength and the field element core of the interface processing method and materials to ensure bond strength between the old and the new concrete, it was to derive the construction site construction method that can improve the performance of the bond strength through a review of the construction around the correlations and the bond strength according to the effective performance analysis of the conventional surface treatment process and variation of polymer volume fraction.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.1215-1224
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• 2013

Great efforts have been made worldwide to reduce the Green House Gas (GHG) emission following the "Kyoto Protocol" declared during the United Nations Framework Convention on Climate Change in 1997. Many industries have restructured to meet the standard set by the Protocol. However, no clear guidance has been established for the purpose of reducing the GHG emission in construction industry. In addition, no significant effort has been made to conserve the energy during construction activities. For more effective energy saving in construction industry, it is essential to collect data about energy consumption, quantity of environmental emissions and costs. However, most studies on sustainable construction have been concentrated on the use of equipment, maintenance and repair works during construction due to the difficulties of collecting such data. This study suggests a method to select the most environmentally friendly equipment combination for earthwork with comparing environmental loads and costs using the database of Life Cycle Inventory in the Ministry of Knowledge Economy and Ministry of Environment of Korea.

• Structural Engineering and Mechanics
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• v.52 no.2
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• pp.391-403
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• 2014

In this study an innovative method of earthquake-resistant strengthening of reinforced concrete structures is presented for the first time. Strengthening according to this new method consists of the construction of steel fiber high-strength concrete jackets without conventional reinforcement which is usually applied in the construction of conventional reinforced concrete jackets (i.e., longitudinal reinforcement, stirrups, hoops). The proposed in this study innovative steel fiber high-strength or ultra high-strength concrete jackets were proved to be much more effective than the reinforced concrete jackets and the FRP-jackets when used for the earthquake-resistant strengthening of reinforced concrete structural members.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.04a
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• pp.182-187
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• 1993

Recent increasing traffic volumes have made many bridges on highway be widened. In widening of existing bridges, construction joints between old and new parts of concrete slabs are subjected to repeated traffic loads during placing and during of concrete. Therefore, the main goal of this paper is given to investigate the variation of the shear strength of widening deck. As a result, the occurrence of cracks in vibrating specimen is faster than that of non-vibrating one, and most of cracks are occurred at new concrete. And the difference of shear strength in vibrating specimen is larger than non-vibrating one, but the difference is negligible. Also, it shows the same result about direct and non-shrinkage joint specimen test.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.725-730
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• 1998

In the nuclear power plant, steel or polymer liner plates are adopted to prohibit inner concrete surface contacting with gas or liquid materials. If there is an accident, the plate will be damaged, and concrete shall have final responsibility to safety requirements. In this paper, an experimental research was carried out to investigate the effects of construction joint and wet and loading condition on the permeability of concrete. The test results showed that leakage rate is decreased much more at the following cases than the others : (a)wet condition, (b)without a construction joint case, and (c)case subjected to external loads. It was noted that more reinforcement is required at the latter case.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.1
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• pp.40-49
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• 2004

In this paper, vibration response of aerial gas pipeline due to vehicle loads was quantitatively estimated through experiment and analysis in open cut construction site. The vehicle vibration of various construction machines causes serious effect to the aerial gas pipeline. The new vibration prediction equations presented in this study can estimate the vibration velocity response of the aerial gas pipeline. In the nitration prediction equations, the vehicle′s weight and traveling velocity, which are the sources of vibration, are combined into the term called, "scaled weight" Methods to reduce vibration were proposed in case the vibration velocity response of the gas pipeline exceeded the vibration criterion, using the vibration prediction equations presented in this study. One was to limit the vehicle′s traveling velocity and the other to install the isolation equipment. Both methods can be estimated quantitatively.